Radio navigating system



5 Sheets-Sheet 2 Original Filed Jan. 19, 1929 INVENTOR.

d lwl k ATTORNEY- Aug. 13, 1935. J. A. WILLOUGHBY RADIO NAVIGATINGSYSTEM Original Filed Jan. 19, 1929 3 Sheets-Sheet 3 IN V EN TOR. John.A. Willuuglfllg ATTORNEY Patented Aug. 13, 1935 Original applicationJanuary 19, 1929, Serial No.

333,703, now Patent No. 1,898,474, dated February 21, 1933.

Divided and this application July 16, 1932, Serial No. 622,937

14 Claims.

(Granted under the act of March 3, 1883, as

amended April 30, 1928; 3'70 0. G. 757) My invention relates broadly toapparatus for aiding navigation of aircraft and more particularly to acircuit arrangement for the receiving apparatus of a navigation systemfor aircraft.

This application is a division of my application Serial No. 333,703,filed January 19, 1929, entitled Aircraft landing system, which issuedinto Patent No. 1,898,474 on February 21, 1933.

One of the objects of my invention is to provide a receiving circuitarrangement responsive to combined radiant and radio frequency energyfor guiding aircraft to a landing port and indicating the position ofthe landing field.

Another object of my invention is to provide a circuit arrangement forradio navigating apparatus for aircraft by which the position of theaircraft with respect to a propagated beam of radio frequency energy maybe accurately determined and the location of a landing field indicatedon the aircraft when the craft passes over the landing field.

Still another object of my invention is to provide a circuit arrangementfor radio navigation systems on aircraft in which both the direction oftravel for the aircraft and the location of the landing fields along thecourse of travel may be definitely indicated to the pilot.

A further object of my invention is to provide an indicator circuit forradio navigating systems operative under the combined influence ofradiant and radio frequency energy for indicating both a navigablecourse and the position of landing fields with respect to the navigablecourse.

A still further object of my invention is to'provide a circuitarrangement of radio navigating systems in which the functioning of anindicator on the aircraft is controlled by the combined action of radiofrequency energy received from a directively propagated beam and radiantenergy received from a landing field for informing the pilot of anaircraft as to the position of the aircraft under condition of fog ordarkness.

Another object of my invention is to provide a circuit arrangement foran indicator for radio navigation systems in which light sensitive cellsare connected to control the operation of certain of the electron tubesof an indicator circuit independently of the operation of such electrontubes by received radio frequency energy from a directively propagatedbeam.

Other and further objects of my invention reside in the circuitarrangement for an indicator system for aircraft as set forth more fullyin the specification hereinafter following by reference to theaccompanying drawings, in which:

Figure 1 is a schematic and diagrammatic view of one circuit arrangementfor a radio navigating apparatus embodying my invention; Fig. 2 shows amodified circuit arrangement of increased sensitivity for an indicatorsystem embodying my invention; and Fig. 3 shows a further modified formof indicator apparatus embodying my invention.

In the circuit arrangement of my invention, I provide radio frequencyenergy pick-up circuits having differing directive characteristicselectrically connected with separate electron tube circuits. Theseparate electron tube circuits have their outputs connected withseparate indicators. A generator is provided for periodically andsuccessively energizing the plate circuits of the separate electron tubesystems so that the electron tube systems are alternately operative forreceiving signaling energy incident upon the radio frequency energypick-up means. When the aircraft, on which the apparatus is arranged, isdirectly upon the course of a directively propagated beam of radiofrequency energy, visual indicator lamps alternately glow withsubstantially equal intensity. If the aircraft departs from thepredetermined course, one indicator lamp is caused to glow with greaterintensity than the other indicator lamp according to a lateraldisplacement of the aircraft with respect to the directly propagatedbeam. My invention contemplates the location of a source of radiantenergy propagated upwardly from each landing field. Light sensitivecells are arranged to control the'circuits of the electron tube systems,which cells are energized when the craft moves into a position over thesource of radiant energy at the landing field. Energization of the lightsensitive cells serves to block the operation of the electron tubecircuits and correspondingly deenergize the indicators. When the radiantenergy is rendered intermittent by chopping, then the indicator lampsare caused to flicker alternately and intermittently in accordance withthe action of the radio frequency energy incident upon the radiofrequency energy pick-up circuits and the action of the radiant energyon the light sensitive cells connected with the electron tube circuits.

The radiant energy at each of the landing fields may be infra-red raysor visible or invisible rays which are detectible aboard the aircraft byop eration of the light sensitive cells. The radiant energy transmittedfrom the landing field effects the operation of the apparatus on theaircraft simultaneously with the operation of the apparatus by the radiofrequency energy on the directively propagated beam. In order to enablethe pilot to be informed of the height of the aircraft over the landingfield, electromagnetic radiation transmitted from the landing field maybe more, whereas the visible radiation may extend to a height offive'thousand feet or more. The.

area covered by the electromagnetic radiation propagated from the loopantenna at the land- 7 ing port may have a diameter of the orderof fivemiles at the height of five thousand feet,

.whereas the diameter of the area covered by the visible radiation oradjacent spectra may be only one mile at the same height. I 1 7 Byobserving the indications of the different instruments While operatingthe aircraft over the landing field, the pilot or navigator will'be ableto determine over which portion of the field the aircraft is operating.In case of fog or darkness, the centrally located source of radiationsin the visible or adjacent spectra may be caused to emit rays of highfogpenetrating power which affect photoelectric cells positioned uponthe aircraft and inform the pilot that the craft is over the field.Energy radiated from the loop antenna system at the landing port isreceived by suitable antanna positioned upon the aircraft and caused tooperate proper signaling devices where by the pilot determines whetherthe craft is moving into a more or less intense field. In case thesignaling devices, operated through the action of energy transmittedfrom the loop antenna system show that the craft is proceeding to anarea of less intense field strength, the pilot will be. informed by thesignaling system receiving energy from the centrally located beacon, ifthe craft is progressing over the center of the field. The exactlocation of the landing field is thus obtained by the pilot or navigatorof the aircraft. The pilotis, therefore, informed of his entry into theelectromagnetic field above the landing field by the alternateflickering of the visual indicators and is informed of the position ofthe aircraft when centrally of the landing field by the blocking ofelectron tube circuits andthe entinguishing of the visual indicators onthe aircraft.

In Fig. 1 is illustrated a schematic circuit diagram of connectionsillustrating a manner in which theapparatus employed in aircraft inaccordance with this invention is connected. Light sensitive cells 40and 4| which may be of the selenium type or any other type ofphotoelectric cell well known in the art, are connected to the gridelectrodes of the electron discharge devices 42 and 43 respectively.Coupling'devices 44'and 45 are connected to the plate electrodes ofelectron discharge devices 42 and 43 and to the glow lamps t6 and 4?respectively. A low frequency oscillation generator 48 is coupledthrough inductances 49 and 5!, which are included in its circuits, and,

the inductances 553 and 52 to the anode circuits of electron dischargedevices 53 and 54 which include the inductances 5!! and 52 respectively.Grid leak resistances'55 and 58 and grid condensers 55 and 59 areconnected to the grid electrodes of electron discharge devices54 and 53,respectively. Coupling devices 53 and 54 are employed to couple theanode circuits of electron discharge devices 53 and 54 to the gridcircuits of devices 43 and 42, respectively. Variable condensers 5? and55 are connected across the loop antennae 62 and BI respectively and tothe input circuits of electron discharge devices 54 and 53,

respectively. Source A is provided for energizing the filaments ofdevices 42, 43, 53 and 54. Source B is provided for energizing thephotoelectric cells 40 and and the anode circuits of devices 42 and 43.

In operation signals from a signal transmitting station located at anairport are intercepted equally by the directive antennae 6| and 62 ifthe aircraft proceeds directly toward the transmit-.

ting station.. Signaling energy from loop antenna 62 is impressed uponthe input circuit of device 54. Energy from the loop BI is impressedupon the input circuit of the device 53. When the anode of the device 54is electricaliy positive with respect to the cathode by virtue of apositive potential being impressed upon it through the operation of thelow frequency oscillation generator 48, energy modulated in accordancewith signals impressed upon the input circuit of, device 54 is impressedthrough the circuits of the device 42 and transformer 44 upon the glowlamp 4%.

' intensity when'the loop antennae 5i and 62 inter- Likewise when theanode of the device 53 is' electrically positive with respect to itscathode cept signaling energy of equal orrapproximately equal magnitude.

When intermittent rays of radiation impinge upon the photoelectric cells48 and 4%,positive potential is intermittently impressedrupon the gridelectrodes of devices'42 and 43. The glow lamps 46 and 4'! are thuscaused to fiicker alternately and intermittently in accordance with theinterrupted rays transmitted to the light sensitive cells as and 4|.

In Fig. 2 is shown a modified form of the circuit arrangement such asillustrated in'Fig. 1'

wherein electron discharge devices having a plurality of. gridelectrodes whereby the action of the glow lampsdfi and 4'! is moreeffectively controlled by the light sensitive cells 45 and 4! areemployed. The light sensitive cells40 and 4| are connected to the gridelectrodes 42b and 43b of the devices 4211 and 430., respectively.Devices 42a and 43a may be of the shield grid. type or they may bed theplural grid electrode type in which case the light sensitive cells areconnected to-either one of the grid electrodes. The. operation of thecircuit arrangement shown in Fig.2 is substantially the same as theoperation of the circuit arrangement shown in Fig; 1 in that energycollected by the directional antenna 62 is caused to affect theoperation of the glow discharge lamp 46 and the energy collected by. thedirectional antenna 61a is caused to affect the operation of the glowdischarge lamp 41. 1 In Fig. 3 is shown a modified form of the circuitarrangement adapted for usewhere substantially constant radiant energyis transmitted from the source on :the landing field. Photoelectrictron. discharge device 48a, which is connected intoithe circuits of thelow frequencyoscillation generator 48. Relays 46c and 410 are connectedtothe anode electrodes of devices 42 and 43. Lamps 55b and 411) areconnected into circuit with-the source of current supply A and armaturesprovided for the relays 46c and Me. When signaling energies ofsubstantially .equal intensity are impressed upon the input circuits ofdevices 53 and 54, the circuits of both of the lamps 46b and MD areclosed alternately by virtueof the operation of the low frequencyoscillation generator 48. When the aircraft proceeds over the aviationfield and radiant energy such as light rays or adjacent spectra, isintercepted by the. photoelectric cell 40a, the grid electrode ,of thedevice 48a receives -a negativecharge whereby its operation is blockedwhile these radiations are transmitted to the photoelectric cell Theelectron discharge devices 54 and 53 are not energized while theoscillation generator 48 is thus blocked. The currents in the anodecircuits of devices 42 and 43 decrease and the v circuits of the lamps46b and 41b are-opened. 1 The lamps 46b and 41b are, therefore, notenergized when radiant energy is intercepted by the cell 4011..

\ ,The invention herein described, may be manufactured and used by andfor the Government of i the United States of America, for governmentalpurposes, without the payment of any royalties thereon.

' :EWhat I claim as new and desire to secure by Letters Patent of theUnited States is as follows:

IJIna signal translating system adapted to receive signal energy, anaudio frequency amplifying unit, a signal responsive device connectedthereto, a source of electric signal energy, an independent source ofintermittent radiant light energy, a light responsive cell connected incircuit with said audio frequency amplifying unit and means for focusingenergy received from said source of intermittent radiant light energyupon said light responsive cell for interrupting the operation of saidsignal responsive device by said source of electric signal energy.

2. In an electron tube signal indicating system, an electron tube,circuits connecting the input of said tube to a source of electricsignal energy, a source of negative biasing grid potential connected inthe grid circuit of said electron tube, a signal responsive deviceconnected in the output circuit of said electron tube, a light sensitivecell having one terminal connected to the grid of said electron tube andmeans responsive to signaling waves propagated intermittently andindependently of said electric signaling energy, a source of potentialhaving its positive terminal connected to the other terminal of saidlight sensitive cell and having its negative terminal connected to thecathode terminal of said electron tube, whereby the impinging of saidintermittently propagated signaling waves upon said light sensitive cellintermittently interrupts the delivery of energy to said signalresponsive device by said electron tube.

3. An indicator system for aircraft comprising radio frequency energypickup circuits, separate electron tube systems connected with saidcircuits, indicators actuated by said electron tube systems and a lightsensitive cell individual to the input circuit to each of said separateelectron tube systems and operative under control of independently andintermittently propagated radiant energy for controlling the operationof said indicators intermittently by the radio frequency energy suppliedby said pickup circuits and the said intermittently propagated radiantenergy.

4. An indicator system for aircraft operation comprising light energypickup means directional,

radio. frequency energy pickup means for directionally receiving radiofrequency energy, an indicating mechanism connected to said directionalradio frequency energy pickup means, and means operated by said lightenergy pickup means for intermittently blocking the operation of saidindicating mechanism. 5. In an indicating system, a pair of directionalsignal receiving means, means including two alternately operativeindicative devices connected respectively to said receiving'means forshowing a variable response in accordance with a variable directionalrelation of said receiving means with respect to signals transmitted ona given channel, and photo-sensitive means responsive to signalstransmitted on a second channel for interrupting the response of saidalternately operative indicative devices.

6. A system in accordance with claim 5 in which said 1 indicativedevices are gaseous discharge tubes.

7. In an indicating system, a plurality of directional antennae, aplurality of indicating means connected respectively with saiddirectional antennae for variably indicating the relative amplitude ofpickup of radio frequency signals by said directional antennae, andphoto-sensitive means responsive to signals other than those firstmentioned for intermittently suppressing the indications produced bysaid plurality of indicating means.

8. A system in accordance with claim 7 in which said plurality ofindicating means comprises two glow tubes and operating circuitstherefore such that a variable condition of said system with respect tosaid radio frequency signals produces an intensity of luminescence inone tube inversely proportional to that in the other tube.

9. In a system of the class described, two alternately indicativereceptors of radio frequency energy, means for varying the amplitude ofresponse in each receptor inversely with respect to the other, andphotoelectric means responsive to waves propagated independently of saidradio frequency energy for intermittently interrupting the operation ofsaid receptors.

10. In a system of the class described, directional loop antennae andmeans connected therewith for providing a variable indication inresponse to variable directional relations which said antenna bear to acondition of propagating radio frequency signals, and means including adevice responsive to heat or light waves propagated independently ofsaid radio frequency signals for intermittently interrupting the actionof the first said means.

11. In a balanced electron tube signal indicating system, a pair ofelectron tubes, circuits connecting the input of each of said tubes toseparate sources of electric signal energy, a source of negative biasinggrid potential connected in the grid circuit of each of said tubes, asignal responsive device connected to the output circuit of each of saidtubes, a source of intermittently propagated light energy, a pair oflight sensitive cells adapted to be focused 'on said source ofintermittently propagated light energy each having one terminalconnected to the grid of each of said electron tubes, a source ofpotential having its positive terminal connected to the otherterminal'of each of said light sensitive cells and having its negativeterminal connected to the cathode terminals of said electron tubes,whereby the impinging of intermittent light energy upon said lightsensitive cells interrupts the delivery of energy to said signalresponsive devices by said electron tubes.

12'. In an electron tube signal indicating sys-' tem, a signal receivingcircuit including a fourelectrcde electron tube having cathode, anodeand two grids, circuits connecting one of said grids to a source ofelectric signal energy, a signal responsive deviceconnected in theoutput of said electron tube, a light sensitive cell having one terminalconnected to the other grid of said electron tube, and a source ofpotential having its positive terminal connected to the other terminalof said light sensitive cell and having its negative terminal connectedto the cathode terminal of said electron tube, a similar signalreceiving circuit connected with a source of electric signal energywhich is variable with respect to the first mentioned source, the signalresponsive device of said last. mentioned circuit being disposedadjacent the signal responsive device oi.

said first mentioned circuit for indicating the relative strength of thesignal energy at said sources, said light sensitive cells constitutingmeans whereby the impinging of intermittently propagated light signalsupon said'light sensitive cells successively interrupts the delivery ofenergy to said signal responsive devices.

13. In a balanced electron tube signal indicat ing system, a pair offour-electrode electron tubes 3 each having cathode, anode, and twogrids, circults connecting one grid of each 'of said tubes 7 to a sourceof electric signal energy, a signal responsive device connected in' theoutput circuit of each of said electron tubes, a pair oilight sensitivecells each having 'one terminal connected respectively to the other gridof each of said electron tubes, a source of potential having itspositive'terminal connected to the other terminal of eachv of said lightsensitive cells and having its negativeterminal connected to the cathodeor each of said electron tubes, whereby the impinging of intermittentlypropagated light signals upon said light sensitive cells successivelyinterruptsthe delivery of energy to said signal .responsive devices bysaid electron tubes.

14. In an'indicator for radio navigating apparatus, an audio frequencyamplifier system, an,

indicator connected with the output of said audio frequency amplifiersystem, a light sensitive cell, 7

circuits interconnecting said light sensitive cell with said audiofrequency amplifier system, means for impressing signaling energy on theinput of said audio frequency amplifier system, a similar

